Rules added by plugins
How to add a new plugin:
1. edit __init__.py in plugins folder add your plugin module name
2. create a function pluginInit(filter) in order to add the plugin rules to the filter
3. check irc.py for example
Removed the need for __init__.py list modification in order to insert new plugins
Just put your plugin in the plugins folder, it will work
Mutex on addRule
Removed cleanup regex (issue 6)

changed the filter() method in filter to match for one regex only using groups
adapted the addRule() method
adapted irc plugin to the mentioned changes